diff options
Diffstat (limited to 'include/efi_variable.h')
| -rw-r--r-- | include/efi_variable.h | 236 |
1 files changed, 236 insertions, 0 deletions
diff --git a/include/efi_variable.h b/include/efi_variable.h new file mode 100644 index 0000000000..2c629e4dca --- /dev/null +++ b/include/efi_variable.h @@ -0,0 +1,236 @@ +/* SPDX-License-Identifier: GPL-2.0+ */ +/* + * Copyright (c) 2020, Heinrich Schuchardt <xypron.glpk@gmx.de> + */ + +#ifndef _EFI_VARIABLE_H +#define _EFI_VARIABLE_H + +#include <linux/bitops.h> + +#define EFI_VARIABLE_READ_ONLY BIT(31) + +enum efi_auth_var_type { + EFI_AUTH_VAR_NONE = 0, + EFI_AUTH_VAR_PK, + EFI_AUTH_VAR_KEK, + EFI_AUTH_VAR_DB, + EFI_AUTH_VAR_DBX, + EFI_AUTH_VAR_DBT, + EFI_AUTH_VAR_DBR, +}; + +/** + * efi_get_variable() - retrieve value of a UEFI variable + * + * @variable_name: name of the variable + * @vendor: vendor GUID + * @attributes: attributes of the variable + * @data_size: size of the buffer to which the variable value is copied + * @data: buffer to which the variable value is copied + * @timep: authentication time (seconds since start of epoch) + * Return: status code + */ +efi_status_t efi_get_variable_int(u16 *variable_name, const efi_guid_t *vendor, + u32 *attributes, efi_uintn_t *data_size, + void *data, u64 *timep); + +/** + * efi_set_variable() - set value of a UEFI variable + * + * @variable_name: name of the variable + * @vendor: vendor GUID + * @attributes: attributes of the variable + * @data_size: size of the buffer with the variable value + * @data: buffer with the variable value + * @ro_check: check the read only read only bit in attributes + * Return: status code + */ +efi_status_t efi_set_variable_int(u16 *variable_name, const efi_guid_t *vendor, + u32 attributes, efi_uintn_t data_size, + const void *data, bool ro_check); + +/** + * efi_get_next_variable_name_int() - enumerate the current variable names + * + * @variable_name_size: size of variable_name buffer in byte + * @variable_name: name of uefi variable's name in u16 + * @vendor: vendor's guid + * + * See the Unified Extensible Firmware Interface (UEFI) specification for + * details. + * + * Return: status code + */ +efi_status_t efi_get_next_variable_name_int(efi_uintn_t *variable_name_size, + u16 *variable_name, + efi_guid_t *vendor); + +/** + * efi_query_variable_info_int() - get information about EFI variables + * + * This function implements the QueryVariableInfo() runtime service. + * + * See the Unified Extensible Firmware Interface (UEFI) specification for + * details. + * + * @attributes: bitmask to select variables to be + * queried + * @maximum_variable_storage_size: maximum size of storage area for the + * selected variable types + * @remaining_variable_storage_size: remaining size of storage are for the + * selected variable types + * @maximum_variable_size: maximum size of a variable of the + * selected type + * Returns: status code + */ +efi_status_t efi_query_variable_info_int(u32 attributes, + u64 *maximum_variable_storage_size, + u64 *remaining_variable_storage_size, + u64 *maximum_variable_size); + +#define EFI_VAR_FILE_NAME "ubootefi.var" + +#define EFI_VAR_BUF_SIZE 0x4000 + +/* + * This constant identifies the file format for storing UEFI variables in + * struct efi_var_file. + */ +#define EFI_VAR_FILE_MAGIC 0x0161566966456255 /* UbEfiVa, version 1 */ + +/** + * struct efi_var_entry - UEFI variable file entry + * + * @length: length of enty, multiple of 8 + * @attr: variable attributes + * @time: authentication time (seconds since start of epoch) + * @guid: vendor GUID + * @name: UTF16 variable name + */ +struct efi_var_entry { + u32 length; + u32 attr; + u64 time; + efi_guid_t guid; + u16 name[]; +}; + +/** + * struct efi_var_file - file for storing UEFI variables + * + * @reserved: unused, may be overwritten by memory probing + * @magic: identifies file format, takes value %EFI_VAR_FILE_MAGIC + * @length: length including header + * @crc32: CRC32 without header + * @var: variables + */ +struct efi_var_file { + u64 reserved; + u64 magic; + u32 length; + u32 crc32; + struct efi_var_entry var[]; +}; + +/** + * efi_var_to_file() - save non-volatile variables as file + * + * File ubootefi.var is created on the EFI system partion. + * + * Return: status code + */ +efi_status_t efi_var_to_file(void); + +/** + * efi_var_restore() - restore EFI variables from buffer + * + * @buf: buffer + * Return: status code + */ +efi_status_t efi_var_restore(struct efi_var_file *buf); + +/** + * efi_var_from_file() - read variables from file + * + * File ubootefi.var is read from the EFI system partitions and the variables + * stored in the file are created. + * + * In case the file does not exist yet or a variable cannot be set EFI_SUCCESS + * is returned. + * + * Return: status code + */ +efi_status_t efi_var_from_file(void); + +/** + * efi_var_mem_init() - set-up variable list + * + * Return: status code + */ +efi_status_t efi_var_mem_init(void); + +/** + * efi_var_mem_find() - find a variable in the list + * + * @guid: GUID of the variable + * @name: name of the variable + * @next: on exit pointer to the next variable after the found one + * Return: found variable + */ +struct efi_var_entry *efi_var_mem_find(const efi_guid_t *guid, const u16 *name, + struct efi_var_entry **next); + +/** + * efi_var_mem_del() - delete a variable from the list of variables + * + * @var: variable to delete + */ +void efi_var_mem_del(struct efi_var_entry *var); + +/** + * efi_var_mem_ins() - append a variable to the list of variables + * + * The variable is appended without checking if a variable of the same name + * already exists. The two data buffers are concatenated. + * + * @variable_name: variable name + * @vendor: GUID + * @attributes: variable attributes + * @size1: size of the first data buffer + * @data1: first data buffer + * @size2: size of the second data field + * @data2: second data buffer + * @time: time of authentication (as seconds since start of epoch) + * Result: status code + */ +efi_status_t efi_var_mem_ins(u16 *variable_name, + const efi_guid_t *vendor, u32 attributes, + const efi_uintn_t size1, const void *data1, + const efi_uintn_t size2, const void *data2, + const u64 time); + +/** + * efi_var_mem_free() - determine free memory for variables + * + * Return: maximum data size plus variable name size + */ +u64 efi_var_mem_free(void); + +/** + * efi_init_secure_state - initialize secure boot state + * + * Return: status code + */ +efi_status_t efi_init_secure_state(void); + +/** + * efi_auth_var_get_type() - convert variable name and guid to enum + * + * @name: name of UEFI variable + * @guid: guid of UEFI variable + * Return: identifier for authentication related variables + */ +enum efi_auth_var_type efi_auth_var_get_type(u16 *name, const efi_guid_t *guid); + +#endif |